I am also a happy FireFox user, but recently I have found a growing number of websites that won't even let you use their functionality unless you are using Chrome or Safari (Fluid for one: https://www.fluidui.com/editor/live/). It must have something to do with FF's support of certain capabilities, although specifically what I'm not sure.
This is pushing me to use Chrome for those reasons - so I hope that FF fills whatever gap is causing sites to exclude FF (oh, and IE, Opera, etc.)
Half the time the UA sniffing has nothing to do with capabilities and just has to do with people only wanting to test in one browser and use only one set of prefixed CSS properties...
> I am also a happy FireFox user, but recently I have found a growing number of websites that won't even let you use their functionality unless you are using Chrome or Safari
This seems unlikely as FireFox user share was bigger then Chrome until recently and is much bigger then Safari. Except for Mobile, where I think the dominance of Android/ios has led to a lot of use of webkit specific features.
It's not that unlikely when Google is the author of some of these sites, sadly. At this point they seem to have a policy of writing Chrome-specific things first and then maybe making it work in other browsers and maybe not.
I find (especially on my phone) that sites often have no idea what does and doesn't work in recent versions of Firefox. Sadly, it is worth spoofing your user agent to check whether or not they are right.
This is pushing me to use Chrome for those reasons - so I hope that FF fills whatever gap is causing sites to exclude FF (oh, and IE, Opera, etc.)